α-Amino-iso-Butyric Acid Foldamers Terminated with Rhodium(I) N-Heterocyclic Carbene Catalysts
David P Tilly1,2, William Cullen1,2, Heng Zhong1,2
1Manchester Institute of Biotechnology, University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|December 21, 2021
Summary
Researchers synthesized peptide foldamers with rhodium complexes to study remote ligand folding effects on catalysis. Chirality was successfully relayed down the foldamer, but did not alter catalytic stereoselectivity, suggesting future control pathways.
Area of Science:
- Organometallic Chemistry
- Supramolecular Chemistry
- Catalysis
Background:
- Organometallic complexes are crucial catalysts, but their efficiency can be limited by ligand conformation.
- Peptide foldamers offer a tunable scaffold for controlling molecular architecture and function.
Purpose of the Study:
- To synthesize and study dynamic peptide foldamers with rhodium(I) N-heterocyclic carbene (NHC) complexes.
- To investigate the influence of remote ligand folding on the catalytic activity of organometallic complexes.
- To explore the potential for remote conformational control in catalysis.
Main Methods:
- Synthesis of α-amino-iso-butyric acid (Aib) peptide foldamers bearing rhodium(I) NHC complexes.
- X-ray crystallography to determine the structure of foldamer-metal complexes.
- Nuclear Magnetic Resonance (NMR) spectroscopy to analyze diastereoisomer ratios and conformational preferences.
- Hydrosilylation reactions to assess catalytic activity and stereoselectivity.
Main Results:
- Synthesized foldamers with varying N-terminal residues and a C-terminal Rh(NHC) complex.
- X-ray crystallography revealed a distorted 310 helical structure and axial chirality in the rhodium complex.
- NMR spectroscopy demonstrated the transmission of chiral conformational information from N-terminal residues to the rhodium center.
- Remote chiral residues did not influence the stereoselectivity of the hydrosilylation reactions catalyzed by these foldamers.
Conclusions:
- Chiral information can be effectively relayed through a 1 nm helical foldamer to an axially chiral organometallic complex.
- While remote conformational control was achieved, it did not translate to altered stereoselectivity in the studied catalytic reactions.
- These findings provide a foundation for developing novel strategies for remote conformational control of organometallic catalysts.
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